Alkaline cleaning materials have been the source of intensive research and development for many years. Such products take the form of aqueous liquids, powders, pellets and solid blocks. In a number of markets such as warewashing and laundry, where safety and efficiency are paramount, solid block detergents have become a detergent of choice. Solid block compositions offer unique advantages over conventional detergents including improved handling and safety, elimination of component segregation during transportation and storage and increased concentration of active components within the composition. Further, the materials can be made in a hydrated form which produces less heat of hydration when dispensed. The materials disclosed in Fernholz, U.S. Reissue Pat. Nos. 2,763 and 32,818 quickly replaced conventional powder and liquid forms of detergents in a number of industrial and institutional markets.
The detergents are typically used by dispensing the detergent with a water spray-on dispenser. In the dispenser, the detergent is combined with a major proportion of water producing a detergent concentrate solution that is added to wash water in a washing machine to form a wash solution. The wash solution, when contacted with a soiled article, successfully removes the soil from the article. Such detergency (soil removal) is most commonly obtained from a source of alkalinity used in manufacturing the detergent. Sources of alkalinity can include alkali metal hydroxides, alkali metal silicates, alkali metal carbonates and other typically inorganic based materials. Additional detergency can be obtained from the use of surfactant materials. Typically, anionic or nonionic surfactants are formulated into such detergents with other ingredients to obtain compositions that can be used to form cleaning solutions having substantial soil removal while controlling foam action. A number of optional detergent ingredients can enhance soil removal, but primarily soil removal is obtained from the alkalinity source and the anionic or nonionic surfactant.
One typical ingredient used in manufacturing cast solid detergents includes a hardness ion sequestering composition. Such compositions are used to soften water by sequestering typically divalent and trivalent metal ions that are commonly found in varying type and compositions of water drawn from local water utilities. Depending on geographical location, service water can contain substantial quantities of ferrous, ferric, manganese, magnesium, calcium and other divalent or trivalent inorganic species that can be present in hard water. Most locales have differing types and concentration of such inorganic species in the water. Typically greater than about 150 ppm of hardness ions determined as calcium is considered hard water in most locales. Most hardness sequestering agents act to complex such hardness ions using multivalent anionic inorganic and organic species. The most common inorganic sequestering agent, in these applications, comprises a condensed phosphate hardness sequestering agent such as tripolyphosphate, hexametaphosphate, pyrophosphate and other such phosphate materials. Similarly, more expensive organic sequestering agents are also known but are not preferred. Organic sequestering agents such as nitrilotriacetic acid, ethylene diamine tetraacetic acid, nitrilotriphosphonic acid, 1-(hydroxyethylidene)-1,1-diphosphonic acid and others have been known for many years to be effective sequestrants for detergents used in aqueous systems. One commonly available inorganic sequestrant, sodium tripolyphosphate is known to have protein peptizing capacity that tends to aid in the suspension of protein in washing solutions used in warewashing. However, to date sequestering agents have not been known to provide cleaning properties to detergent compositions.
Jacobsen, U.S. Pat. No. 4,105,573 discloses the use of a combination of an alkyl phosphonate, wherein the alkyl group contains 10-24 carbon atoms, with a particular class of alcohol ethoxylates to exhibit soil releasing effect. The preferred material is an octadecane phosphonate. Leikhim et al., U.S. Pat. No. 4,284,532 disclose an isotropic liquid using a phosphate ester or a "hydrophilic surfactant" such as sodium xylene sulfonate to couple with a builder and a surfactant in a cleaning composition. The cleaning composition can contain as a builder, DEQUEST-2010, 1-hydroxy-11-ethylidene diphosphonate or a similar phosphonate compound.
Baeck et al., U.S. Pat. No. 5,019,292 teach a fabric softening clay in a laundry detergent. Ethylene diamine tetramethylene phosphonic acid is used as a builder in certain examples without other sequestrant compositions.
Krummel et al, U.S. Pat. No. 3,985,669, Campbell et al., U.S. Pat. No. 4,216,125; O'Brien et al., U.S. Pat. No. 4,268,406; Corkill et al., U.S. Pat. No. 4,274,975; Ward et al., U.S. Pat. No. 4,359,413; Corkill et al., U.S. Pat. No. 4,605,509; Lewis, U.S. Pat. No. 4,698,181; and Bruegge et al., U.S. Pat. No. 5,061,392 teach that organic phosphonates can be successful co-builders that function by chelation of additional calcium and magnesium ions. Note that Lewis, U.S. Pat. No. 4,698,181 teaches that the overall detergent composition is successful at removing organic soil stains such as food and beverage stains. Glogowski et al., U.S. Pat. No. 4,983,315 teach a technology similar to that disclosed above and specifically teach that chelation agents can bind transition metals in soils to enhance cleaning performances.
Lastly, Bartolotia et al., U.S. Pat. No. 4,000,080; Rose, U.S. Pat. No. 4,072,621; Schwuger et al., U.S. Pat. No. 4,148,603; and Ferry, U.S. Pat. No. 4,276,205 teach that certain combinations of builders (not a combination of a condensed phosphate and an organophosphonate) provide good results in a particular application. The prior art shown here does not suggest that improved soil release capacity can be obtained by combining a condensed phosphate sequestrant with an organophosphonate sequestrant.
In any highly competitive market, a substantial need exists in improving the properties of detergent systems. In improving such systems, the cleaning properties of the systems are examined for the purpose of obtaining sufficient cleaning of all types of soils including inorganic soils, food soils such as fats, carbohydrates and proteins and organic soils obtained from the environment such as hydrocarbon oils, pigments, lipstick, etc. Such improved detergents can obtain adequate cleaning of a variety of soils at reduced concentrations.